Method for recovering metal ions in aqueous liquid

Abstract

Esters of comenic acid were found to form metal chelate compounds with various metal ions and these chelate compounds are soluble in organic solvents. This finding makes it possible to recover or remove metal ions from industrial drainage and the like.

What is claimed is: 
     
       1. A method for recovering metal ions in aqueous liquid which comprises maintaining the pH of the aqueous liquid at not less than 3 and contacting said aqueous liquid containing metal ions with an effective recovering amount of a comenic ester wherein the alcohol group contains at least 3 carbon atoms in a hydrophobic solvent. 
     
     
       2. A method of claim 1, wherein the metal ion is a member selected from the group consisting of Fe, Cu, Cd, Pb, Ni, Co, Zn, Au, Pt, Al, Sb, Bi, Sn, Cr, Y and UO 2 . 
     
     
       3. A method of claim 1, wherein the comenic ester is a member selected from the group consisting of a lower alkyl, middle alkyl, higher alkyl, aralkyl and cycloalkyl ester of comenic acid. 
     
     
       4. A method of claim 1, wherein the hydrophobic solvent is a member selected from the group consisting of benzene, toluene, xylene, chloroform, 1,2-dichloroethane, and trichloroethylene. 
     
     
       5. A method of claim 1, wherein the pH is from 4 to 7. 
     
     
       6. A method for recovering metal ions in aqueous liquid which comprises contacting a comenic ester wherein the alcohol group contains at least 3 carbon atoms and said ester is selected from the group consisting of a lower alkyl, middle alkyl, higher alkyl, aralkyl and cycloalkyl ester of comenic acid dissolved in a hydrophobic solvent selected from the group consisting of benzene, toluene, xylene, chloroform, dichloroethane and trichloroethylene with the aqueous liquid containing metal ions, with the pH of the aqueous layer being maintained at not less than three. 
     
     
       7. A method of claim 6, wherein the comenic ester is a C 5  -C 8  aliphatic hydrocarbon ester and the solvent is 1,2-dichloroethane and the pH is four to seven. 
     
     
       8. A method of claim 6, wherein the comenic ester is amyl ester and the solvent is 1,2-dichloroethane and the pH is four to seven. 
     
     
       9. A method of claim 7, wherein the comenic ester is octyl ester and the solvent is 1,2-dichloroethane and the pH is four. 
     
     
       10. The method of claim 1, wherein the alcohol group of said comenic ester is propyl, butyl, isobutyl, amyl, isoamyl, octyl, nonyl, lauryl, myristyl, benzyl or cyclohexyl. 
     
     
       11. The method of claim 6, wherein the alcohol group of said comenic ester is propyl, butyl, isobutyl, amyl, isoamyl, octyl, nonyl, lauryl, myristyl, benzyl or cyclohexyl.